As the technology based on the multi terminal flexible direct current of the VSC and DC power grid comes to be used, the quick direct current circuit breaker becomes the key device to ensure the system running security, stability and reliability. In the exchange system, the alternating current has two natural zero-crossing points in a period, the alternating current circuit breaker just uses the current natural zero-crossing point to cut off the current, meanwhile the direct current has no natural zero-crossing point, therefor, the cut off of the direct current is far more different than the cut off of the alternating current.
Generally speaking, there are two method to cut off the direct current, one is based on the general alternating mechanical switch, superimposing increasing oscillation current on direct current of the arcing gap by adding auxiliary circuit, cutting off the circuit by the current passes through zero, and the mechanical switch breaker is manufactured by this principle, it cannot meet the demands of the multi terminal flexible direct current transmission system on the breaking time; Another is that a high power cut-off power electronic device is used to break the direct current directly, although the solid-state breaker manufactured by this principle can meet the demands of the multi terminal flexible direct current transmission system on the breaking time, it has an oversize loss and poor economic nature when it is turned on normally.